READING, England — A teacher’s tape recording of Prince Harry allegedly admitting he cheated on an art exam was insufficient to warrant a renewed investigation into the incident, an examination board said Friday.

Sarah Forsyth, a former teacher who claims she was unfairly dismissed from Eton College after being ordered to help Harry cheat on an exam, tried to prove her allegation to an employment tribunal on Thursday by using a secret tape recording she had made while talking to him. Forsyth, 30, is seeking $18,000 in compensation for unfair dismissal.

Forsyth has told the tribunal she wrote nearly all the text of an art project that Harry submitted to pass an important exam in 2002. The grade that Harry received for the course work helped him win admission to his next school, Sandhurst, where he will train as a military officer.

A previous investigation by the exam board found Harry, the son of Prince Charles and the late Princess Diana, had not cheated.

Forsyth claims she was fired on June 16, 2003 from Eton, one of Britain’s most prestigious private elementary and secondary schools, after being harassed by Ian Burke, then head of Eton’s art department. She said Burke ordered her to do some of the work on Harry’s art project.

Forsyth’s attorney, Robin Allen, quoted Harry as saying on the tape: “It was a tiny, tiny bit. I did about a sentence of it.” Forsyth claims the prince was referring to the amount of work he had done on the course materials submitted to the exam board.

The examining board, Edexcel, said the teacher’s evidence was not enough to warrant a new investigation into the alleged cheating.

“Edexcel has now reviewed the tape both by listening to it and reading the transcript provided for the tribunal,” said board spokeswoman Stevie Pattison-Dick.

“It has been determined that the tape is inconclusive and not sufficiently evidentiary grounds to warrant the reopening of the malpractice investigation in this instance.”

Eton later released its own transcript of the tape, with Prince Harry something slightly different: “I was, like, a sentence in it.”

Paddy Harverson, a spokesman for Prince Charles, said Thursday: “This is incredibly unfair on Harry. Miss Forsyth’s lawyers have given the court a brief extract from the tape and placed their own interpretation upon it.”